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Triterpenoids Isolated from Apple Peels Have Potent Antiproliferative

Activity and May Be Partially Responsible for Apple's Anticancer Activity

Xiangjiu He and Rui Hai Liu*

Department of Food Science and Institute of Comparative and

Environmental Toxicology, Cornell University, Ithaca, New York 14853

Abstract:

Bioactivity-guided fractionation of apple peels was used to determine

the chemical identity of bioactive constituents. Thirteen

triterpenoids were isolated, and their chemical structures were

identified. Antiproliferative activities of the triterpenoids against

human HepG2 liver cancer cells, MCF-7 breast cancer cells, and Caco-2

colon cancer cells were evaluated. Most of the triterpenoids showed

high potential anticancer activities against the three human cancer

cell lines. Among the compounds isolated, 2-hydroxyursolic acid,

2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic

acid, and 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid

showed higher antiproliferative activity toward HepG2 cancer cells.

Ursolic acid, 2-hydroxyursolic acid, and

3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid exhibited

higher antiproliferative activity against MCF-7 cancer cells. All

triterpenoids tested showed antiproliferative activity against Caco-2

cancer cells, especially 2-hydroxyursolic acid, maslinic acid,

2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic

acid, and 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid,

which displayed much higher antiproliferative activities. These

results showed the triterpenoids isolated from apple peels have potent

antiproliferative activity and may be partially responsible for the

anticancer activities of whole apples.

Apple's Power May Lie in the Peel

Apple's Anticancer Compounds Concentrated in the Peel

By Warner

WebMD Medical News

Reviewed by Brunilda Nazario, MD

May 18, 2007 -- Apples may be appealing for a very good reason. A new

study shows the bulk of apples' anticancer properties lie in the peel.

Researchers analyzed the chemical composition of apple peels and

identified a group of phytochemicals that proved potent against at

least three different types of human cancer cells: breast, colon, and

liver.

Countless studies have supported the old adage " An apple a day keeps

the doctor away " by showing a diet rich in fruits and vegetables

reduces the risk of cancer, heart disease, diabetes, and a host of

other chronic diseases.

But researchers say they're just beginning to understand exactly which

compounds found in fruits and vegetables are responsible for these

healthy benefits. Much of the recent research has focused on the

anticancer properties of a group of phytochemicals known as phenolics,

which are typically found in the seeds and skins of fruit and vegetables.

Testing Apple's Appeal

Apples are the largest source of phenolics in the American diet,

representing 22% of all fruit phenolics consumed in the U.S. The

average phenolic content of an apple ranges from 110 milligrams to 347

milligrams per 100 grams of fresh apple. Apples are also high in

another group of healthful compounds known as flavonoids.

In the study, published in the Journal of Agricultural and Food

Chemistry, researchers processed 231 pounds of Red Delicious apples

and extracted the chemical content of about 24 pounds of apple peel.

They then screened the chemical compounds for potential anticancer

properties and identified a group of phytochemicals with powerful

anticancer effects. The results showed apple peels had more potent

antioxidant activity and anticell proliferation properties against

human cancer cells than apple flesh did.

Researchers say the study shows that apple peel may account for the

lion's share of apple's anticancer and antidisease properties and

should be regarded as a rich source of nutrients and antioxidants.

SOURCES: He, X. Journal of Agricultural and Food Chemistry, May 8,

2007 online edition. News release, Journal of Agricultural and Food

Chemistry.